1. Field of the invention
This invention relates to an electrical connection terminal, and more particularly to an electrical connection terminal with an excellent electrical conductivity suited for a device requiring a large current.
2. Related art
As shown in FIGS. 6 and 7, as a conventional electrical connection terminal for a large current, there has heretofore been used a box-like female connection member which includes an electrical contact member mounted therein, this electrical contact member for receiving a male connection member including a rigid metal plate of a good electrical conductivity resiliently deformed into the shape of .OMEGA.. This female connection member comprises two elements, and one of them is a box-like female connection member body 100 which includes a bottom plate 101 of a U-shaped cross-section having a compressively-clamping conductor connection portion 102 formed at its rear portion, a pair of generally-upstanding side wall plates 103 spaced along the length of the bottom plate, and top plates 104 formed by bending distal portions of the side wall plates in such a manner that the top plates 104 are disposed parallel to the bottom plate 101. The other element is the electrical contact member 15, and the opposite end portions of the .OMEGA.-shaped metal plate are curved outwardly away from each other to provide diverging guide portions 106 for easily receiving a tongue-like male member. Throat portions 107 are continuous with the guide portions 106, respectively, and are projected inwardly toward each other for direct sliding contact with the tongue-like male member. A pair of upper and lower oppositely-extending, retaining projections 108 are provided at opposite ends of the electrical contact member 105 for positioning the electrical contact member between the pair of side wall plates and for contacting the contact member with the bottom plate 101. For assembling the electrical connection member, the retaining projections 108 are fitted between the pair of side wall plates 103 to position the electrical contact member 105, and then the side wall plates 103 and the upper plates 104 are bent until this portion is formed into a rectangular cross-section, thereby mounting the electrical contact member in the female connection member body 100. Further, a conductor 110 is received in the conductor clamping portion 102 while a conductor covering 109 is received in a covering clamping portion 103, and then these portions are compressed at their periphery, thus completing the assembling.
In use, a socket A (connected to an equipment) having a male connection member M is held between the throat portions 107 of the electrical contact member 105 mounted in the electrical connection member body 100. Therefore, electric current flows from the conductor 110 to the retaining projections 108 of the electrical contact member 105 through the conductor clamping portion 102, the bottom plate 101, the side wall plates 103 and the upper plates 104, and further flows to the male connection member M through the throat portions 107. Thus, the current flow into the male connection member via several point-contact portions.
Generally, when the above connection member is to be used in an equipment requiring a large current, it is necessary to take care to prevent the generation of heat and an arc. Therefore, it is necessary to reduce an electric resistance at the areas of contact between the two. To achieve this, it is important to eliminate as much as possible those areas of contact where the members of different electrical conductivities are contacted with each other. The reason is that current (general characteristics of electricity) flows from a high-resistance portion (low-conductivity portion) to a low-resistance portion (high-conductivity portion). If it is intended to flow a large current by contacting a high-conductivity member with a low-conductivity member, the current will not flow toward the low-conductivity member, and if it is intended to forcibly flow the current through the low-conductivity member (high-resistance member), the member generates heat, and this is quite dangerous.
Generally, however, for manufacturing reasons, the female connection member (the one element) is made of zinc soft iron plate or a brass plate which has good workability, and the electrical contact member (the other element) is made of a phosphor bronze plate or a copper plate which is inferior in workability. The former is inferior in electrical conductivity to the latter, and therefore it is clear that a large electrical resistance develops between the two members, thus causing the above-mentioned problem.